Final answer:
Copernicus developed a heliocentric model of the solar system where Earth revolves around the Sun. He correctly ordered the planets based on their distances from the Sun and recognized the relationship between a planet's distance from the Sun and its orbital speed.
Step-by-step explanation:
Copernicus developed a heliocentric model of the solar system, which he described in his book De Revolutionibus Orbium Coelestium. In this model, Earth is one of the planets that revolve around the Sun. Copernicus placed the planets in the correct order of their distances from the Sun: Mercury, Venus, Earth, Mars, Jupiter, and Saturn. He also deduced that the closer a planet is to the Sun, the faster its orbital speed.